In the type of reactor this invention concerns, the head of the movable valve element on the drainage assemblies is housed in the evacuation space of the drainage orifice so as to free the outlet area when the movable element of the drainage assembly is in the upper open position.
Conventionally, when in the closed position, this head rests on a seating made of chemically resistant synthetic material, for example, PTFE.
Therefore, according to the prior art technique, this seating is formed in the upper portion of a sealing piece with a tubular body and a circular base forming a peripheral blocking and maintaining shoulder. The upper portion of this sealing piece serves as a seating for the movable element of the seal assembly and its lower shoulder portion acts as a sealing surface against the projecting portion of the drainage orifice pipe. The tubular portion is introduced into the evacuation pipe of the drainage orifice. It is adapted to the diameter of this evacuation pipe and its shoulder blocks and maintains it in place penetrating the pipe.
On its other surface, this tubular seating and sealing piece is applied tightly against the upper flanged rim of the drainage assembly body.
This prior art technique has several important disadvantages.
The first disadvantage relates to retention of product which happens in the interstice located between the seating and the drainage pipe. This causes cross-contamination of products during two successive uses of the reactor. Actually, the adjustment between the seating and sealing element and the evacuation pipe is not perfect. Some product originating from the reaction in progress penetrates the small space that exists between this element and the interior lateral surface of the evacuation pipe of the outlet orifice.
This small space is quasi-inaccessible, making it difficult or even impossible for cleaning and disinfection products to penetrate it, such that the remaining liquid constitutes a source of cross-contamination between the two products of two successive reactions; this is hardly desirable and even contraindicated, especially in the food and pharmaceutical industries.
Moreover, the product trapped in this interstice may crystallize, causing serious difficulties when detaching the valve and consequently a high risk that the enamel coating will deteriorate.